SiberianTiger
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Updates Voyager mission news
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tblaxland
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No, I guess there has not been sufficient news on the Voyager mission since the forum opened (Oct 07)We didn't have such thread, did we?
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NASA JPL:
New Project Manager as Voyager Explores New Territory
October 29, 2010
PASADENA, Calif. - As NASA's two Voyager spacecraft hurtle towards the edge of our solar system, a new project manager will shepherd the spacecraft into this unexplored territory: Suzanne Dodd, whose first job at NASA's Jet Propulsion Laboratory in Pasadena, Calif., involved sequencing science and engineering commands for Voyager 1 and 2 in 1984.
"I'm thrilled to re-join a pioneering mission that set up adventures for so many other spacecraft to follow," Dodd said. "There will be more firsts to come as we gather unique data once the spacecraft reach interstellar space. There isn't a single mission currently on the books that will be doing what Voyager is doing."
The Voyager 2 spacecraft, launched on Aug. 20, 1977, is about 14 billion kilometers (9 billion miles) away from the sun. It is the longest continuously operating NASA spacecraft. The Voyager 1 spacecraft, launched on Sept. 5, 1977, is about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant active spacecraft.
In four to six years, Voyager 1 is expected to cross beyond the heliosheath, the outer layer of the bubble around our solar system that is composed of ionized atoms streaming outward from our sun. Voyager 2 is expected to cross that boundary several years later. Once beyond our heliosheath, the two Voyager spacecraft will begin exploring the interstellar medium, which fills the space between stars.
When Dodd started on Voyager, Voyager 2 was on its way to Uranus. She stayed with the mission until Voyager 2 completed its closest approach to Neptune. No other spacecraft have visited these two outer planets.
Dodd still keeps a rolled-up sheet of vellum in her cabinet that shows the timeline of commands communicated to the spacecraft during its closest approach to Neptune on Aug. 25, 1989. The encounter with our seventh planet revealed the Great Dark Spot, a giant storm roiling Neptune's atmosphere, and geysers erupting from pinkish-hued nitrogen ice that forms the polar cap of Neptune's moon Triton.
After leaving Voyager in October 1989, Dodd moved on to other JPL projects, including NASA's Cassini mission to Saturn. She left JPL in 1999 to work at the Spitzer Science Center, which processes data from NASA's Spitzer Space Telescope, and, later, the Infrared Processing and Analysis Center, which archives infrared astronomy data from many sources. Dodd eventually managed both those centers, which are based at the California Institute of Technology in Pasadena.
"Coming back to Voyager is like re-learning a language you knew as a kid, but never spoke as an adult," said Dodd. "I'm excited to be immersed in the details again."
Dodd was also recently named the Spitzer Space Telescope's new project manager.
Dodd says the main challenge with Voyager now is to work within the boundaries of the spacecrafts' limited resources to make sure they collect the long-anticipated interstellar data. For example, Voyager's radioisotope power generators, which use heat from the decay of plutonium to produce electricity, have enabled the spacecraft to operate for this extended period of time, so far away from the sun. But the power, as expected, decays over time. While supplies are expected to last through 2020, Dodd and the operations team will eventually have to turn off some instruments to manage the power resources.
"My job is to make sure the two spacecraft stay healthy and mobile," she said.
Dodd is a native of Gig Harbor, Wash., a town outside of Tacoma. She graduated with a bachelors of arts degree in math from Whitman College in Walla Walla, Wash., and a bachelors of science degree in mechanical engineering from Caltech. She also holds a masters degree in aerospace engineering from the University of Southern California in Los Angeles.
Nine Voyager project managers preceded Dodd: H.M. "Bud" Schurmeier (1972-76), John Casani (1976-77), Robert Parks (1978-79), Raymond Heacock (1979-81), Esker Davis (1981-82), Richard Laeser (1982-86), Norman Haynes (1987-89), George Textor (1989-97) and Ed Massey (1998 to 2010). Edward C. Stone is the Voyager project scientist.
The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA.
More information on Voyager is at http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov.
----------------------------------------
Space Travel: Interstellar Voyage Continues With New Project Manager.
New Project Manager as Voyager Explores New Territory
October 29, 2010
PASADENA, Calif. - As NASA's two Voyager spacecraft hurtle towards the edge of our solar system, a new project manager will shepherd the spacecraft into this unexplored territory: Suzanne Dodd, whose first job at NASA's Jet Propulsion Laboratory in Pasadena, Calif., involved sequencing science and engineering commands for Voyager 1 and 2 in 1984.
"I'm thrilled to re-join a pioneering mission that set up adventures for so many other spacecraft to follow," Dodd said. "There will be more firsts to come as we gather unique data once the spacecraft reach interstellar space. There isn't a single mission currently on the books that will be doing what Voyager is doing."
The Voyager 2 spacecraft, launched on Aug. 20, 1977, is about 14 billion kilometers (9 billion miles) away from the sun. It is the longest continuously operating NASA spacecraft. The Voyager 1 spacecraft, launched on Sept. 5, 1977, is about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant active spacecraft.
In four to six years, Voyager 1 is expected to cross beyond the heliosheath, the outer layer of the bubble around our solar system that is composed of ionized atoms streaming outward from our sun. Voyager 2 is expected to cross that boundary several years later. Once beyond our heliosheath, the two Voyager spacecraft will begin exploring the interstellar medium, which fills the space between stars.
When Dodd started on Voyager, Voyager 2 was on its way to Uranus. She stayed with the mission until Voyager 2 completed its closest approach to Neptune. No other spacecraft have visited these two outer planets.
Dodd still keeps a rolled-up sheet of vellum in her cabinet that shows the timeline of commands communicated to the spacecraft during its closest approach to Neptune on Aug. 25, 1989. The encounter with our seventh planet revealed the Great Dark Spot, a giant storm roiling Neptune's atmosphere, and geysers erupting from pinkish-hued nitrogen ice that forms the polar cap of Neptune's moon Triton.
After leaving Voyager in October 1989, Dodd moved on to other JPL projects, including NASA's Cassini mission to Saturn. She left JPL in 1999 to work at the Spitzer Science Center, which processes data from NASA's Spitzer Space Telescope, and, later, the Infrared Processing and Analysis Center, which archives infrared astronomy data from many sources. Dodd eventually managed both those centers, which are based at the California Institute of Technology in Pasadena.
"Coming back to Voyager is like re-learning a language you knew as a kid, but never spoke as an adult," said Dodd. "I'm excited to be immersed in the details again."
Dodd was also recently named the Spitzer Space Telescope's new project manager.
Dodd says the main challenge with Voyager now is to work within the boundaries of the spacecrafts' limited resources to make sure they collect the long-anticipated interstellar data. For example, Voyager's radioisotope power generators, which use heat from the decay of plutonium to produce electricity, have enabled the spacecraft to operate for this extended period of time, so far away from the sun. But the power, as expected, decays over time. While supplies are expected to last through 2020, Dodd and the operations team will eventually have to turn off some instruments to manage the power resources.
"My job is to make sure the two spacecraft stay healthy and mobile," she said.
Dodd is a native of Gig Harbor, Wash., a town outside of Tacoma. She graduated with a bachelors of arts degree in math from Whitman College in Walla Walla, Wash., and a bachelors of science degree in mechanical engineering from Caltech. She also holds a masters degree in aerospace engineering from the University of Southern California in Los Angeles.
Nine Voyager project managers preceded Dodd: H.M. "Bud" Schurmeier (1972-76), John Casani (1976-77), Robert Parks (1978-79), Raymond Heacock (1979-81), Esker Davis (1981-82), Richard Laeser (1982-86), Norman Haynes (1987-89), George Textor (1989-97) and Ed Massey (1998 to 2010). Edward C. Stone is the Voyager project scientist.
The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA.
More information on Voyager is at http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov.
----------------------------------------
Space Travel: Interstellar Voyage Continues With New Project Manager.
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3 times in a lifespan of Internet... Two weeks later...
________________________________________
NASA JPL:
Saturn Then and Now: 30 Years Since Voyager Visit
November 11, 2010
Ed Stone, project scientist for NASA's Voyager mission, remembers the first time he saw the kinks in one of Saturn's narrowest rings. It was the day the Voyager 1 spacecraft made its closest approach to the giant ringed planet, 30 years ago. Scientists were gathering in front of television monitors and in one another's offices every day during this heady period to pore over the bewildering images and other data streaming down to NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Stone drew a crude sketch of this scalloped, multi-stranded ring, known as the F ring, in his notebook, but with no explanation next to it. The innumerable particles comprising the broad rings are in near-circular orbits about Saturn. So, it was a surprise to find that the F ring, discovered just a year before by NASA's Pioneer 11 spacecraft, had clumps and wayward kinks. What could have created such a pattern?
"It was clear Voyager was showing us something different at Saturn," said Stone, now based at the California Institute of Technology in Pasadena. "Over and over, the spacecraft revealed so many unexpected things that it often took days, months and even years to figure them out."
The F ring curiosity was only one of many strange phenomena discovered in the Voyager close encounters with Saturn, which occurred on Nov. 12, 1980, for Voyager 1, and Aug. 25, 1981, for Voyager 2. The Voyager encounters were responsible for finding six small moons and revealing the half-young, half-old terrain of Enceladus that had to point to some kind of geological activity.
Images from the two encounters also exposed individual storms roiling the planet's atmosphere, which did not show up at all in data from Earth-based telescopes. Scientists used Voyager data to resolve a debate about whether Titan had a thick or thin atmosphere, finding that Titan was shrouded in a thick haze of hydrocarbons in a nitrogen-rich atmosphere. The finding led scientists to predict there could be seas of liquid methane and ethane on Titan's surface.
"When I look back, I realize how little we actually knew about the solar system before Voyager," Stone added. "We discovered things we didn't know were there to be discovered, time after time."
In fact, the Voyager encounters sparked so many new questions that another spacecraft, NASA's Cassini, was sent to probe those mysteries. While Voyager 1 got to within about 126,000 kilometers (78,300 miles) above Saturn's cloud tops, and Voyager 2 approached as close as about 100,800 kilometers (62,600 miles), Cassini has dipped to this altitude and somewhat lower in its orbits around Saturn since 2004.
Because of Cassini's extended journey around Saturn, scientists have found explanations for many of the mysteries first seen by Voyager. Cassini has uncovered a mechanism to explain the new terrain on Enceladus – tiger stripe fissures with jets of water vapor and organic particles. It revealed that Titan indeed does have stable lakes of liquid hydrocarbons on its surface and showed just how similar to Earth that moon really is. Data from Cassini have also resolved how two small moons discovered by Voyager – Prometheus and Pandora – tug on the F ring to create its kinked shape and wakes that form snowballs.
"Cassini is indebted to Voyager for its many fascinating discoveries and for paving the way for Cassini," said Linda Spilker, Cassini project scientist at JPL, who started her career working on Voyager from 1977 to 1989. "On Cassini, we still compare our data to Voyager's and proudly build on Voyager's heritage."
But Voyager left a few mysteries that Cassini has not yet solved. For instance, scientists first spotted a hexagonal weather pattern when they stitched together Voyager images of Saturn's north pole. Cassini has obtained higher-resolution pictures of the hexagon – which tells scientists it's a remarkably stable wave in one of the jet streams that remains 30 years later – but scientists are still not sure what forces maintain the hexagon.
Even more perplexing are the somewhat wedge-shaped, transient clouds of tiny particles that Voyager discovered orbiting in Saturn's B ring. Scientists dubbed them "spokes" because they looked like bicycle spokes. Cassini scientists have been searching for them since the spacecraft first arrived. As Saturn approached equinox, and the sun's light hit the rings edge-on, the spokes did reappear in the outer part of Saturn's B ring. But Cassini scientists are still testing their theories of what might be causing these odd features.
"The fact that we still have mysteries today goes to show how much we still have to learn about our solar system," said Suzanne Dodd, Voyager's project manager, based at JPL. "Today, the Voyager spacecraft continue as pioneers traveling toward the edge of our solar system. We can't wait for the Voyager spacecraft to enter interstellar space – true outer space – and make more unexpected discoveries."
Voyager 1, which was launched on Sept. 5, 1977, is currently about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant spacecraft. Voyager 2, which was launched on Aug. 20, 1977, is currently about 14 billion kilometers (9 billion miles) away from the sun.
The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages Cassini for NASA. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.
________________________________________
NASA JPL:
Saturn Then and Now: 30 Years Since Voyager Visit
November 11, 2010
Ed Stone, project scientist for NASA's Voyager mission, remembers the first time he saw the kinks in one of Saturn's narrowest rings. It was the day the Voyager 1 spacecraft made its closest approach to the giant ringed planet, 30 years ago. Scientists were gathering in front of television monitors and in one another's offices every day during this heady period to pore over the bewildering images and other data streaming down to NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Stone drew a crude sketch of this scalloped, multi-stranded ring, known as the F ring, in his notebook, but with no explanation next to it. The innumerable particles comprising the broad rings are in near-circular orbits about Saturn. So, it was a surprise to find that the F ring, discovered just a year before by NASA's Pioneer 11 spacecraft, had clumps and wayward kinks. What could have created such a pattern?
"It was clear Voyager was showing us something different at Saturn," said Stone, now based at the California Institute of Technology in Pasadena. "Over and over, the spacecraft revealed so many unexpected things that it often took days, months and even years to figure them out."
The F ring curiosity was only one of many strange phenomena discovered in the Voyager close encounters with Saturn, which occurred on Nov. 12, 1980, for Voyager 1, and Aug. 25, 1981, for Voyager 2. The Voyager encounters were responsible for finding six small moons and revealing the half-young, half-old terrain of Enceladus that had to point to some kind of geological activity.
Images from the two encounters also exposed individual storms roiling the planet's atmosphere, which did not show up at all in data from Earth-based telescopes. Scientists used Voyager data to resolve a debate about whether Titan had a thick or thin atmosphere, finding that Titan was shrouded in a thick haze of hydrocarbons in a nitrogen-rich atmosphere. The finding led scientists to predict there could be seas of liquid methane and ethane on Titan's surface.
"When I look back, I realize how little we actually knew about the solar system before Voyager," Stone added. "We discovered things we didn't know were there to be discovered, time after time."
In fact, the Voyager encounters sparked so many new questions that another spacecraft, NASA's Cassini, was sent to probe those mysteries. While Voyager 1 got to within about 126,000 kilometers (78,300 miles) above Saturn's cloud tops, and Voyager 2 approached as close as about 100,800 kilometers (62,600 miles), Cassini has dipped to this altitude and somewhat lower in its orbits around Saturn since 2004.
Because of Cassini's extended journey around Saturn, scientists have found explanations for many of the mysteries first seen by Voyager. Cassini has uncovered a mechanism to explain the new terrain on Enceladus – tiger stripe fissures with jets of water vapor and organic particles. It revealed that Titan indeed does have stable lakes of liquid hydrocarbons on its surface and showed just how similar to Earth that moon really is. Data from Cassini have also resolved how two small moons discovered by Voyager – Prometheus and Pandora – tug on the F ring to create its kinked shape and wakes that form snowballs.
"Cassini is indebted to Voyager for its many fascinating discoveries and for paving the way for Cassini," said Linda Spilker, Cassini project scientist at JPL, who started her career working on Voyager from 1977 to 1989. "On Cassini, we still compare our data to Voyager's and proudly build on Voyager's heritage."
But Voyager left a few mysteries that Cassini has not yet solved. For instance, scientists first spotted a hexagonal weather pattern when they stitched together Voyager images of Saturn's north pole. Cassini has obtained higher-resolution pictures of the hexagon – which tells scientists it's a remarkably stable wave in one of the jet streams that remains 30 years later – but scientists are still not sure what forces maintain the hexagon.
Even more perplexing are the somewhat wedge-shaped, transient clouds of tiny particles that Voyager discovered orbiting in Saturn's B ring. Scientists dubbed them "spokes" because they looked like bicycle spokes. Cassini scientists have been searching for them since the spacecraft first arrived. As Saturn approached equinox, and the sun's light hit the rings edge-on, the spokes did reappear in the outer part of Saturn's B ring. But Cassini scientists are still testing their theories of what might be causing these odd features.
"The fact that we still have mysteries today goes to show how much we still have to learn about our solar system," said Suzanne Dodd, Voyager's project manager, based at JPL. "Today, the Voyager spacecraft continue as pioneers traveling toward the edge of our solar system. We can't wait for the Voyager spacecraft to enter interstellar space – true outer space – and make more unexpected discoveries."
Voyager 1, which was launched on Sept. 5, 1977, is currently about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant spacecraft. Voyager 2, which was launched on Aug. 20, 1977, is currently about 14 billion kilometers (9 billion miles) away from the sun.
The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages Cassini for NASA. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.
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NASA JPL:
NASA Probe Sees Solar Wind Decline
December 13, 2010
PASADENA, Calif. – The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.
Now hurtling toward interstellar space some 17.4 billion kilometers (10.8 billion miles) from the sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.
The event is a major milestone in Voyager 1's passage through the heliosheath, the turbulent outer shell of the sun's sphere of influence, and the spacecraft's upcoming departure from our solar system.
"The solar wind has turned the corner," said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. "Voyager 1 is getting close to interstellar space."
Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.
Launched on Sept. 5, 1977, Voyager 1 crossed the termination shock in December 2004 into the heliosheath. Scientists have used data from Voyager 1's Low-Energy Charged Particle Instrument to deduce the solar wind's velocity. When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft's speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 17 billion kilometers (10.6 billion miles) from the sun.
Because the velocities can fluctuate, scientists watched four more monthly readings before they were convinced the solar wind's outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 20 kilometers per second each year (45,000 mph each year) since August 2007, when the solar wind was speeding outward at about 60 kilometers per second (130,000 mph). The outward speed has remained at zero since June.
The results were presented today at the American Geophysical Union meeting in San Francisco.
"When I realized that we were getting solid zeroes, I was amazed," said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again."
Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere's structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate Voyager 1 will cross that frontier in about four years.
"In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts," said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece. "Once again, we face the predicament of redoing our models."
A sister spacecraft, Voyager 2, was launched in Aug. 20, 1977 and has reached a position 14.2 billion kilometers (8.8 billion miles) from the sun. Both spacecraft have been traveling along different trajectories and at different speeds. Voyager 1 is traveling faster, at a speed of about 17 kilometers per second (38,000 mph), compared to Voyager 2's velocity of 15 kilometers per second (35,000 mph). In the next few years, scientists expect Voyager 2 to encounter the same kind of phenomenon as Voyager 1.
NASA Probe Sees Solar Wind Decline
December 13, 2010
PASADENA, Calif. – The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.
Now hurtling toward interstellar space some 17.4 billion kilometers (10.8 billion miles) from the sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.
The event is a major milestone in Voyager 1's passage through the heliosheath, the turbulent outer shell of the sun's sphere of influence, and the spacecraft's upcoming departure from our solar system.
"The solar wind has turned the corner," said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. "Voyager 1 is getting close to interstellar space."
Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.
Launched on Sept. 5, 1977, Voyager 1 crossed the termination shock in December 2004 into the heliosheath. Scientists have used data from Voyager 1's Low-Energy Charged Particle Instrument to deduce the solar wind's velocity. When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft's speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 17 billion kilometers (10.6 billion miles) from the sun.
Because the velocities can fluctuate, scientists watched four more monthly readings before they were convinced the solar wind's outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 20 kilometers per second each year (45,000 mph each year) since August 2007, when the solar wind was speeding outward at about 60 kilometers per second (130,000 mph). The outward speed has remained at zero since June.
The results were presented today at the American Geophysical Union meeting in San Francisco.
"When I realized that we were getting solid zeroes, I was amazed," said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again."
Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere's structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate Voyager 1 will cross that frontier in about four years.
"In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts," said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece. "Once again, we face the predicament of redoing our models."
A sister spacecraft, Voyager 2, was launched in Aug. 20, 1977 and has reached a position 14.2 billion kilometers (8.8 billion miles) from the sun. Both spacecraft have been traveling along different trajectories and at different speeds. Voyager 1 is traveling faster, at a speed of about 17 kilometers per second (38,000 mph), compared to Voyager 2's velocity of 15 kilometers per second (35,000 mph). In the next few years, scientists expect Voyager 2 to encounter the same kind of phenomenon as Voyager 1.
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NASA / NASA JPL:
Voyager Celebrates 25 Years Since Uranus Visit
January 21, 2011
As NASA's Voyager 2 spacecraft made the only close approach to date of our mysterious seventh planet Uranus 25 years ago, Project Scientist Ed Stone and the Voyager team gathered at NASA's Jet Propulsion Laboratory, Pasadena, Calif., to pore over the data coming in.
Images of the small, icy Uranus moon Miranda were particularly surprising. Since small moons tend to cool and freeze over rapidly after their formation, scientists had expected a boring, ancient surface, pockmarked by crater-upon-weathered-crater. Instead they saw grooved terrain with linear valleys and ridges cutting through the older terrain and sometimes coming together in chevron shapes. They also saw dramatic fault scarps, or cliffs. All of this indicated that periods of tectonic and thermal activity had rocked Miranda's surface in the past.
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The scientists were also shocked by data showing that Uranus' magnetic north and south poles were not closely aligned with the north-south axis of the planet's rotation. Instead, the planet's magnetic field poles were closer to the Uranian equator. This suggested that the material flows in the planet's interior that are generating the magnetic field are closer to the surface of Uranus than the flows inside Earth, Jupiter and Saturn are to their respective surfaces.
"Voyager 2's visit to Uranus expanded our knowledge of the unexpected diversity of bodies that share the solar system with Earth," said Stone, who is based at the California Institute of Technology in Pasadena. "Even though similar in many ways, the worlds we encounter can still surprise us."
Voyager 2 was launched on Aug. 20, 1977, 16 days before its twin, Voyager 1. After completing its prime mission of flying by Jupiter and Saturn, Voyager 2 was sent on the right flight path to visit Uranus, which is about 3 billion kilometers (2 billion miles) away from the sun. Voyager 2 made its closest approach – within 81,500 kilometers (50,600 miles) of the Uranian cloud tops – on Jan. 24, 1986.
Before Voyager 2's visit, scientists had to learn about Uranus by using Earth-based and airborne telescopes. By observing dips in starlight as a star passed behind Uranus, scientists knew Uranus had nine narrow rings. But it wasn't until the Voyager 2 flyby that scientists were able to capture for the first time images of the rings and the tiny shepherding moons that sculpted them. Unlike Saturn's icy rings, they found Uranus' rings to be dark gray, reflecting only a few percent of the incident sunlight.
Scientists had also determined an average temperature for Uranus (59 Kelvin, or minus 350 degrees Fahrenheit) before this encounter, but the distribution of that temperature came as a surprise. Voyager showed there was heat transport from pole to pole in Uranus' atmosphere that maintained the same temperature at both poles, even though the sun was shining directly for decades on one pole and not the other.
By the end of the Uranus encounter and science analysis, data from Voyager 2 enabled the discovery of 11 new moons and two new rings, and generated dozens of science papers about the quirky seventh planet.
Voyager 2 moved on to explore Neptune, the last planetary target, in August 1989. It is now hurtling toward interstellar space, which is the space between stars. It is about 14 billion kilometers (9 billion miles) away from the sun. Voyager 1, which explored only Jupiter and Saturn before heading on a faster track toward interstellar space, is about 17 billion kilometers (11 billion miles) away from the sun.
"The Uranus encounter was one of a kind," said Suzanne Dodd, Voyager project manager, based at JPL. "Voyager 2 was healthy and durable enough to make it to Uranus and then to Neptune. Currently both Voyager spacecraft are on the cusp of leaving the sun's sphere of influence and once again blazing a trail of scientific discovery."
{...}
Voyager Celebrates 25 Years Since Uranus Visit
January 21, 2011
As NASA's Voyager 2 spacecraft made the only close approach to date of our mysterious seventh planet Uranus 25 years ago, Project Scientist Ed Stone and the Voyager team gathered at NASA's Jet Propulsion Laboratory, Pasadena, Calif., to pore over the data coming in.
Images of the small, icy Uranus moon Miranda were particularly surprising. Since small moons tend to cool and freeze over rapidly after their formation, scientists had expected a boring, ancient surface, pockmarked by crater-upon-weathered-crater. Instead they saw grooved terrain with linear valleys and ridges cutting through the older terrain and sometimes coming together in chevron shapes. They also saw dramatic fault scarps, or cliffs. All of this indicated that periods of tectonic and thermal activity had rocked Miranda's surface in the past.
Click on images for details and their larger versions
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These two pictures of Uranus -- one in true color (left) and the other in false color -- were compiled from images returned Jan. 17, 1986, by the narrow-angle camera of Voyager 2. Image credit: NASA/JPL
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Miranda, innermost of Uranus' large satellites, is seen at close range in this Voyager 2 image, taken Jan. 24, 1986, as part of a high-resolution mosaicing sequence. Image credit: NASA/JPL
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Voyager 2 has discovered two "shepherd" satellites associated with the rings of Uranus. The two moons -- designated 1986U7 and 1986U8 -- are seen here on either side of the bright epsilon ring; all nine of the known Uranian rings are visible. Image credit: NASA/JPL
The scientists were also shocked by data showing that Uranus' magnetic north and south poles were not closely aligned with the north-south axis of the planet's rotation. Instead, the planet's magnetic field poles were closer to the Uranian equator. This suggested that the material flows in the planet's interior that are generating the magnetic field are closer to the surface of Uranus than the flows inside Earth, Jupiter and Saturn are to their respective surfaces.
"Voyager 2's visit to Uranus expanded our knowledge of the unexpected diversity of bodies that share the solar system with Earth," said Stone, who is based at the California Institute of Technology in Pasadena. "Even though similar in many ways, the worlds we encounter can still surprise us."
Voyager 2 was launched on Aug. 20, 1977, 16 days before its twin, Voyager 1. After completing its prime mission of flying by Jupiter and Saturn, Voyager 2 was sent on the right flight path to visit Uranus, which is about 3 billion kilometers (2 billion miles) away from the sun. Voyager 2 made its closest approach – within 81,500 kilometers (50,600 miles) of the Uranian cloud tops – on Jan. 24, 1986.
Before Voyager 2's visit, scientists had to learn about Uranus by using Earth-based and airborne telescopes. By observing dips in starlight as a star passed behind Uranus, scientists knew Uranus had nine narrow rings. But it wasn't until the Voyager 2 flyby that scientists were able to capture for the first time images of the rings and the tiny shepherding moons that sculpted them. Unlike Saturn's icy rings, they found Uranus' rings to be dark gray, reflecting only a few percent of the incident sunlight.
Scientists had also determined an average temperature for Uranus (59 Kelvin, or minus 350 degrees Fahrenheit) before this encounter, but the distribution of that temperature came as a surprise. Voyager showed there was heat transport from pole to pole in Uranus' atmosphere that maintained the same temperature at both poles, even though the sun was shining directly for decades on one pole and not the other.
By the end of the Uranus encounter and science analysis, data from Voyager 2 enabled the discovery of 11 new moons and two new rings, and generated dozens of science papers about the quirky seventh planet.
Voyager 2 moved on to explore Neptune, the last planetary target, in August 1989. It is now hurtling toward interstellar space, which is the space between stars. It is about 14 billion kilometers (9 billion miles) away from the sun. Voyager 1, which explored only Jupiter and Saturn before heading on a faster track toward interstellar space, is about 17 billion kilometers (11 billion miles) away from the sun.
"The Uranus encounter was one of a kind," said Suzanne Dodd, Voyager project manager, based at JPL. "Voyager 2 was healthy and durable enough to make it to Uranus and then to Neptune. Currently both Voyager spacecraft are on the cusp of leaving the sun's sphere of influence and once again blazing a trail of scientific discovery."
{...}
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Almost 34 years old and they still work near perfectly enabling the return of science from a place that no probe has been to be before, seeking out new answers to old questions and returning data that will one day help us to leave the solar system.
Voyager, I salute you.
Voyager, I salute you.
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NASA / NASA JPL:
Voyager Set to Enter Interstellar Space
April 28, 2011
More than 30 years after they left Earth, NASA's twin Voyager probes are now at the edge of the solar system. Not only that, they're still working. And with each passing day they are beaming back a message that, to scientists, is both unsettling and thrilling.
The message is, "Expect the unexpected."
"It's uncanny," says Ed Stone of the California Institute of Technology in Pasadena, Voyager Project Scientist since 1972. "Voyager 1 and 2 have a knack for making discoveries."
Today, April 28, 2011, NASA held a live briefing to reflect on what the Voyager mission has accomplished--and to preview what lies ahead as the probes prepare to enter the realm of interstellar space in our Milky Way galaxy.
The adventure began in the late 1970s when the probes took advantage of a rare alignment of outer planets for an unprecedented Grand Tour. Voyager 1 visited Jupiter and Saturn, while Voyager 2 flew past Jupiter, Saturn, Uranus and Neptune. (Voyager 2 is still the only probe to visit Uranus and Neptune.)
When pressed to name the top discoveries from those encounters, Stone pauses, not for lack of material, but rather an embarrassment of riches. "It's so hard to choose," he says.
Stone's partial list includes the discovery of volcanoes on Jupiter's moon Io; evidence for an ocean beneath the icy surface of Europa; hints of methane rain on Saturn's moon Titan; the crazily-tipped magnetic poles of Uranus and Neptune; icy geysers on Neptune's moon Triton; planetary winds that blow faster and faster with increasing distance from the sun.
"Each of these discoveries changed the way we thought of other worlds," says Stone.
In 1980, Voyager 1 used the gravity of Saturn to fling itself slingshot-style out of the plane of the solar system. In 1989, Voyager 2 got a similar assist from Neptune. Both probes set sail into the void.
Sailing into the void sounds like a quiet time, but the discoveries have continued.
Stone sets the stage by directing our attention to the kitchen sink. "Turn on the faucet," he instructs. "Where the water hits the sink, that's the sun, and the thin sheet of water flowing radially away from that point is the solar wind. Note how the sun 'blows a bubble' around itself."
There really is such a bubble, researchers call it the "heliosphere," and it is gargantuan. Made of solar plasma and magnetic fields, the heliosphere is about three times wider than the orbit of Pluto. Every planet, asteroid, spacecraft, and life form belonging to our solar system lies inside.
The Voyagers are trying to get out, but they're not there yet. To locate them, Stone peers back into the sink: "As the water [or solar wind] expands, it gets thinner and thinner, and it can't push as hard. Abruptly, a sluggish, turbulent ring forms. That outer ring is the heliosheath--and that is where the Voyagers are now."
The heliosheath is a very strange place, filled with a magnetic froth no spacecraft has ever encountered before, echoing with low-frequency radio bursts heard only in the outer reaches of the solar system, so far from home that the sun is a mere pinprick of light.
"In many ways, the heliosheath is not like our models predicted," says Stone.
In June 2010, Voyager 1 beamed back a startling number: zero. That's the outward velocity of the solar wind where the probe is now. No one thinks the solar wind has completely stopped; it may have just turned a corner. But which way? Voyager 1 is trying to figure that out through a series of "weather vane" maneuvers, in which the spacecraft turns itself in a different direction to track the local breeze. The old spacecraft still has some moves left, it seems.
No one knows exactly how many more miles the Voyagers must travel before they "pop free" into interstellar space. Most researchers believe, however, that the end is near. "The heliosheath is 3 to 4 billion miles in thickness," estimates Stone. "That means we'll be out within five years or so."
There is plenty of power for the rest of the journey. Both Voyagers are energized by the radioactive decay of a Plutonium 238 heat source. This should keep critical subsystems running through at least 2020.
After that, he says, "Voyager will become our silent ambassador to the stars."
Each probe is famously equipped with a Golden Record, literally, a gold-coated copper phonograph record. It contains 118 photographs of Earth; 90 minutes of the world's greatest music; an audio essay entitled Sounds of Earth (featuring everything from burbling mud pots to barking dogs to a roaring Saturn 5 liftoff); greetings in 55 human languages and one whale language; the brain waves of a young woman in love; and salutations from the secretary general of the United Nations. A team led by Carl Sagan assembled the record as a message to possible extraterrestrial civilizations that might encounter the spacecraft.
"A billion years from now, when everything on Earth we've ever made has crumbled into dust, when the continents have changed beyond recognition and our species is unimaginably altered or extinct, the Voyager record will speak for us," wrote Carl Sagan and Ann Druyan in an introduction to a CD version of the record.
Some people note that the chance of aliens finding the Golden Record is fantastically remote. The Voyager probes won't come within a few light years of another star for some 40,000 years. What are the odds of making contact under such circumstances?
On the other hand, what are the odds of a race of primates evolving to sentience, developing spaceflight, and sending the sound of barking dogs into the cosmos?
Expect the unexpected, indeed.
{...}
NASA / NASA JPL:
Five Things About NASA's Voyager Mission
April 27, 2011
Here are five facts about NASA's twin Voyager 1 and 2 spacecraft, the longest continuously-operating spacecraft in deep space. The Voyagers were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft.
1. Long-Distance Space Runners
Voyager 2 launched on Aug. 20, 1977, and Voyager 1 launched about two weeks later, on Sept. 5. Since then, the spacecraft have been traveling along different flight paths and at different speeds. Now some 17.4 billion kilometers (10.8 billion miles) from the sun and hurtling toward interstellar space, Voyager 1 is the farthest human-made object from Earth. Voyager 2 is about 14.2 billion kilometers (8.8 billion miles) from the sun.
2. Can You Hear Me Now?
Both spacecraft are still sending scientific information about their surroundings through NASA's Deep Space Network. A signal from the ground, traveling at the speed of light, takes about 13 hours one way to reach Voyager 2, and 16 hours one way to reach Voyager 1.
3. Planetary Tour
The primary five-year mission of the Voyagers included the close-up exploration of Jupiter and Saturn, Saturn's rings and the larger moons of the two planets. The mission was extended after a succession of discoveries, and between them, the two spacecraft have explored all the giant outer planets of our solar system -- Jupiter, Saturn, Uranus and Neptune, 49 moons, and the systems of rings and magnetic fields those planets possess.
The current mission, the Voyager Interstellar Mission, was planned to explore the outermost edge of our solar system and eventually leave our sun's sphere of influence and enter interstellar space - the space between the stars.
4. The Golden Record
Both Voyager spacecraft carry recorded messages from Earth on golden phonograph records - 12-inch, gold-plated copper disks. A committee chaired by the late astronomer Carl Sagan selected the contents of the records for NASA. The records are cultural time capsules that the Voyagers carry with them to other star systems. They contain images and natural sounds, spoken greetings in 55 languages and musical selections from different cultures and eras.
5. Where No Spacecraft Has Gone Before
Voyager 1 has reached a distant point at the edge of our solar system, where the outward motion of solar wind ceases. The event is the latest milestone in Voyager 1's passage through the heliosheath, the outer shell of the sun's sphere of influence, before entering interstellar space. Interstellar space begins at the heliopause, and scientists estimate Voyager 1 will cross this frontier around 2015.
{...}
NASAtelevision:
A special space science presentation at NASA Headquarters highlights the contributions of the two Voyager spacecraft as they continue their multi-decade journey to the boundaries of our solar system and beyond.
Voyager Set to Enter Interstellar Space
April 28, 2011
More than 30 years after they left Earth, NASA's twin Voyager probes are now at the edge of the solar system. Not only that, they're still working. And with each passing day they are beaming back a message that, to scientists, is both unsettling and thrilling.
The message is, "Expect the unexpected."
"It's uncanny," says Ed Stone of the California Institute of Technology in Pasadena, Voyager Project Scientist since 1972. "Voyager 1 and 2 have a knack for making discoveries."
Today, April 28, 2011, NASA held a live briefing to reflect on what the Voyager mission has accomplished--and to preview what lies ahead as the probes prepare to enter the realm of interstellar space in our Milky Way galaxy.
The adventure began in the late 1970s when the probes took advantage of a rare alignment of outer planets for an unprecedented Grand Tour. Voyager 1 visited Jupiter and Saturn, while Voyager 2 flew past Jupiter, Saturn, Uranus and Neptune. (Voyager 2 is still the only probe to visit Uranus and Neptune.)
When pressed to name the top discoveries from those encounters, Stone pauses, not for lack of material, but rather an embarrassment of riches. "It's so hard to choose," he says.
Stone's partial list includes the discovery of volcanoes on Jupiter's moon Io; evidence for an ocean beneath the icy surface of Europa; hints of methane rain on Saturn's moon Titan; the crazily-tipped magnetic poles of Uranus and Neptune; icy geysers on Neptune's moon Triton; planetary winds that blow faster and faster with increasing distance from the sun.
"Each of these discoveries changed the way we thought of other worlds," says Stone.
In 1980, Voyager 1 used the gravity of Saturn to fling itself slingshot-style out of the plane of the solar system. In 1989, Voyager 2 got a similar assist from Neptune. Both probes set sail into the void.
Sailing into the void sounds like a quiet time, but the discoveries have continued.
Stone sets the stage by directing our attention to the kitchen sink. "Turn on the faucet," he instructs. "Where the water hits the sink, that's the sun, and the thin sheet of water flowing radially away from that point is the solar wind. Note how the sun 'blows a bubble' around itself."
There really is such a bubble, researchers call it the "heliosphere," and it is gargantuan. Made of solar plasma and magnetic fields, the heliosphere is about three times wider than the orbit of Pluto. Every planet, asteroid, spacecraft, and life form belonging to our solar system lies inside.
The Voyagers are trying to get out, but they're not there yet. To locate them, Stone peers back into the sink: "As the water [or solar wind] expands, it gets thinner and thinner, and it can't push as hard. Abruptly, a sluggish, turbulent ring forms. That outer ring is the heliosheath--and that is where the Voyagers are now."
The heliosheath is a very strange place, filled with a magnetic froth no spacecraft has ever encountered before, echoing with low-frequency radio bursts heard only in the outer reaches of the solar system, so far from home that the sun is a mere pinprick of light.
"In many ways, the heliosheath is not like our models predicted," says Stone.
In June 2010, Voyager 1 beamed back a startling number: zero. That's the outward velocity of the solar wind where the probe is now. No one thinks the solar wind has completely stopped; it may have just turned a corner. But which way? Voyager 1 is trying to figure that out through a series of "weather vane" maneuvers, in which the spacecraft turns itself in a different direction to track the local breeze. The old spacecraft still has some moves left, it seems.
No one knows exactly how many more miles the Voyagers must travel before they "pop free" into interstellar space. Most researchers believe, however, that the end is near. "The heliosheath is 3 to 4 billion miles in thickness," estimates Stone. "That means we'll be out within five years or so."
There is plenty of power for the rest of the journey. Both Voyagers are energized by the radioactive decay of a Plutonium 238 heat source. This should keep critical subsystems running through at least 2020.
After that, he says, "Voyager will become our silent ambassador to the stars."
Each probe is famously equipped with a Golden Record, literally, a gold-coated copper phonograph record. It contains 118 photographs of Earth; 90 minutes of the world's greatest music; an audio essay entitled Sounds of Earth (featuring everything from burbling mud pots to barking dogs to a roaring Saturn 5 liftoff); greetings in 55 human languages and one whale language; the brain waves of a young woman in love; and salutations from the secretary general of the United Nations. A team led by Carl Sagan assembled the record as a message to possible extraterrestrial civilizations that might encounter the spacecraft.
"A billion years from now, when everything on Earth we've ever made has crumbled into dust, when the continents have changed beyond recognition and our species is unimaginably altered or extinct, the Voyager record will speak for us," wrote Carl Sagan and Ann Druyan in an introduction to a CD version of the record.
Some people note that the chance of aliens finding the Golden Record is fantastically remote. The Voyager probes won't come within a few light years of another star for some 40,000 years. What are the odds of making contact under such circumstances?
On the other hand, what are the odds of a race of primates evolving to sentience, developing spaceflight, and sending the sound of barking dogs into the cosmos?
Expect the unexpected, indeed.
{...}
NASA / NASA JPL:
Five Things About NASA's Voyager Mission
April 27, 2011
Here are five facts about NASA's twin Voyager 1 and 2 spacecraft, the longest continuously-operating spacecraft in deep space. The Voyagers were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft.
1. Long-Distance Space Runners
Voyager 2 launched on Aug. 20, 1977, and Voyager 1 launched about two weeks later, on Sept. 5. Since then, the spacecraft have been traveling along different flight paths and at different speeds. Now some 17.4 billion kilometers (10.8 billion miles) from the sun and hurtling toward interstellar space, Voyager 1 is the farthest human-made object from Earth. Voyager 2 is about 14.2 billion kilometers (8.8 billion miles) from the sun.
2. Can You Hear Me Now?
Both spacecraft are still sending scientific information about their surroundings through NASA's Deep Space Network. A signal from the ground, traveling at the speed of light, takes about 13 hours one way to reach Voyager 2, and 16 hours one way to reach Voyager 1.
3. Planetary Tour
The primary five-year mission of the Voyagers included the close-up exploration of Jupiter and Saturn, Saturn's rings and the larger moons of the two planets. The mission was extended after a succession of discoveries, and between them, the two spacecraft have explored all the giant outer planets of our solar system -- Jupiter, Saturn, Uranus and Neptune, 49 moons, and the systems of rings and magnetic fields those planets possess.
The current mission, the Voyager Interstellar Mission, was planned to explore the outermost edge of our solar system and eventually leave our sun's sphere of influence and enter interstellar space - the space between the stars.
4. The Golden Record
Both Voyager spacecraft carry recorded messages from Earth on golden phonograph records - 12-inch, gold-plated copper disks. A committee chaired by the late astronomer Carl Sagan selected the contents of the records for NASA. The records are cultural time capsules that the Voyagers carry with them to other star systems. They contain images and natural sounds, spoken greetings in 55 languages and musical selections from different cultures and eras.
5. Where No Spacecraft Has Gone Before
Voyager 1 has reached a distant point at the edge of our solar system, where the outward motion of solar wind ceases. The event is the latest milestone in Voyager 1's passage through the heliosheath, the outer shell of the sun's sphere of influence, before entering interstellar space. Interstellar space begins at the heliopause, and scientists estimate Voyager 1 will cross this frontier around 2015.
{...}
NASAtelevision:
A special space science presentation at NASA Headquarters highlights the contributions of the two Voyager spacecraft as they continue their multi-decade journey to the boundaries of our solar system and beyond.
Grover
Saturn V Misfire
humanity is out of its comfort zone on this one. only the probe knows that the Voyagers are headed towards, or what they're in for. i suppose we could launch another set, designed to go further at the next opportunity... perhaps on orbital construction of a pair of refitted Saturn Vs, bolted together with another Voyager sat at the front... overtaking the voyagers in a matter of days, probably on a collision course for another sun, but what the hell, if anything can break free of the suns SOI, it would be the power of the Saturn V
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NASA / NASA JPL:
Probes Suggest Magnetic Bubbles at Solar System Edge
June 09, 2011
PASADENA, Calif. -- Observations from NASA's Voyager spacecraft, humanity's farthest deep space sentinels, suggest the edge of our solar system may not be smooth, but filled with a turbulent sea of magnetic bubbles.
While using a new computer model to analyze Voyager data, scientists found the sun's distant magnetic field is made up of bubbles approximately 100 million miles (160 million kilometers) wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described in the June 9 edition of the Astrophysical Journal.
Like Earth, our sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind, a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy. The Voyager spacecraft, more than 9 billion miles (14 billion kilometers) away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy.
"The sun's magnetic field extends all the way to the edge of the solar system," said astronomer Merav Opher of Boston University. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up."
Understanding the structure of the sun's magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how the star interacts with the rest of the galaxy.
So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data.
"We are still trying to wrap our minds around the implications of the findings," said University of Maryland physicist Jim Drake, one of Opher's colleagues.
{...}
To view supporting images about the research, visit: http://www.nasa.gov/sunearth .
{...}
NASA:
A Big Surprise from the Edge of the Solar System
June 09, 2011
NASA's Voyager probes are truly going where no one has gone before. Gliding silently toward the stars, 9 billion miles from Earth, they are beaming back news from the most distant, unexplored reaches of the solar system.
Mission scientists say the probes have just sent back some very big news indeed.
It's bubbly out there.
Magnetic bubbles at the edge of the solar system are aboout 100 million miles wide--similar to the distance between Earth and the Sun. Credit: NASA According to computer models, the bubbles are large, about 100 million miles wide, so it would take the speedy probes weeks to cross just one of them. Voyager 1 entered the "foam-zone" around 2007, and Voyager 2 followed about a year later. At first researchers didn't understand what the Voyagers were sensing--but now they have a good idea.
"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."
When a magnetic field gets severely folded like this, interesting things can happen. Lines of magnetic force criss-cross, and "reconnect". (Magnetic reconnection is the same energetic process underlying solar flares.) The crowded folds of the skirt reorganize themselves, sometimes explosively, into foamy magnetic bubbles.
"We never expected to find such a foam at the edge of the solar system, but there it is!" says Opher's colleague, University of Maryland physicist Jim Drake.
Theories dating back to the 1950s had predicted a very different scenario: The distant magnetic field of the sun was supposed to curve around in relatively graceful arcs, eventually folding back to rejoin the sun. The actual bubbles appear to be self-contained and substantially disconnected from the broader solar magnetic field.
Energetic particle sensor readings suggest that the Voyagers are occasionally dipping in and out of the foam—so there might be regions where the old ideas still hold. But there is no question that old models alone cannot explain what the Voyagers have found.
Says Drake: "We are still trying to wrap our minds around the implications of these findings."
The structure of the sun's distant magnetic field—foam vs. no-foam—is of acute scientific importance because it defines how we interact with the rest of the galaxy. Researchers call the region where the Voyagers are now "the heliosheath." It is essentially the border crossing between the Solar System and the rest of the Milky Way. Lots of things try to get across—interstellar clouds, knots of galactic magnetism, cosmic rays and so on. Will these intruders encounter a riot of bubbly magnetism (the new view) or graceful lines of magnetic force leading back to the sun (the old view)?
The case of cosmic rays is illustrative. Galactic cosmic rays are subatomic particles accelerated to near-light speed by distant black holes and supernova explosions. When these microscopic cannonballs try to enter the solar system, they have to fight through the sun's magnetic field to reach the inner planets.
"The magnetic bubbles appear to be our first line of defense against cosmic rays," points out Opher. "We haven't figured out yet if this is a good thing or not."
On one hand, the bubbles would seem to be a very porous shield, allowing many cosmic rays through the gaps. On the other hand, cosmic rays could get trapped inside the bubbles, which would make the froth a very good shield indeed.
So far, much of the evidence for the bubbles comes from the Voyager energetic particle and flow measurements. Proof can also be obtained from the Voyager magnetic field observations and some of this data is also very suggestive. However, because the magnetic field is so weak, the data takes much longer to analyze with the appropriate care. Thus, unraveling the magnetic signatures of bubbles in the Voyager data is ongoing.
"We'll probably discover which is correct as the Voyagers proceed deeper into the froth and learn more about its organization," says Opher. "This is just the beginning, and I predict more surprises ahead."
{...}
NASA Goddard Multimedia:
Voyager Satellites Find Magnetic Bubbles at Edge of Solar System (RELATED VIDEOS AND IMAGES)
Probes Suggest Magnetic Bubbles at Solar System Edge
June 09, 2011
PASADENA, Calif. -- Observations from NASA's Voyager spacecraft, humanity's farthest deep space sentinels, suggest the edge of our solar system may not be smooth, but filled with a turbulent sea of magnetic bubbles.
While using a new computer model to analyze Voyager data, scientists found the sun's distant magnetic field is made up of bubbles approximately 100 million miles (160 million kilometers) wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described in the June 9 edition of the Astrophysical Journal.
Like Earth, our sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind, a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy. The Voyager spacecraft, more than 9 billion miles (14 billion kilometers) away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy.
"The sun's magnetic field extends all the way to the edge of the solar system," said astronomer Merav Opher of Boston University. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up."
Understanding the structure of the sun's magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how the star interacts with the rest of the galaxy.
So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data.
"We are still trying to wrap our minds around the implications of the findings," said University of Maryland physicist Jim Drake, one of Opher's colleagues.
{...}
To view supporting images about the research, visit: http://www.nasa.gov/sunearth .
{...}
NASA:
A Big Surprise from the Edge of the Solar System
June 09, 2011
NASA's Voyager probes are truly going where no one has gone before. Gliding silently toward the stars, 9 billion miles from Earth, they are beaming back news from the most distant, unexplored reaches of the solar system.
Mission scientists say the probes have just sent back some very big news indeed.
It's bubbly out there.
Click on image for larger version
Magnetic bubbles at the edge of the solar system are about 100 million miles wide--similar to the distance between Earth and the Sun.
Magnetic bubbles at the edge of the solar system are aboout 100 million miles wide--similar to the distance between Earth and the Sun. Credit: NASA According to computer models, the bubbles are large, about 100 million miles wide, so it would take the speedy probes weeks to cross just one of them. Voyager 1 entered the "foam-zone" around 2007, and Voyager 2 followed about a year later. At first researchers didn't understand what the Voyagers were sensing--but now they have a good idea.
"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."
When a magnetic field gets severely folded like this, interesting things can happen. Lines of magnetic force criss-cross, and "reconnect". (Magnetic reconnection is the same energetic process underlying solar flares.) The crowded folds of the skirt reorganize themselves, sometimes explosively, into foamy magnetic bubbles.
"We never expected to find such a foam at the edge of the solar system, but there it is!" says Opher's colleague, University of Maryland physicist Jim Drake.
Theories dating back to the 1950s had predicted a very different scenario: The distant magnetic field of the sun was supposed to curve around in relatively graceful arcs, eventually folding back to rejoin the sun. The actual bubbles appear to be self-contained and substantially disconnected from the broader solar magnetic field.
Energetic particle sensor readings suggest that the Voyagers are occasionally dipping in and out of the foam—so there might be regions where the old ideas still hold. But there is no question that old models alone cannot explain what the Voyagers have found.
Says Drake: "We are still trying to wrap our minds around the implications of these findings."
The structure of the sun's distant magnetic field—foam vs. no-foam—is of acute scientific importance because it defines how we interact with the rest of the galaxy. Researchers call the region where the Voyagers are now "the heliosheath." It is essentially the border crossing between the Solar System and the rest of the Milky Way. Lots of things try to get across—interstellar clouds, knots of galactic magnetism, cosmic rays and so on. Will these intruders encounter a riot of bubbly magnetism (the new view) or graceful lines of magnetic force leading back to the sun (the old view)?
Click on images to view larger versions
Artist's interpretation depicting the new view of the heliosphere. The heliosheath is filled with "magnetic bubbles" (shown in the red pattern) that fill out the region ahead of the heliopause. In this new view, the heliopause is not a continuous shield that separates the solar domain from the interstellar medium, but a porous membrane with fingers and indentations.
Credit: NASA/Goddard Space Flight Center/ CI Lab
Artist's interpretation of the "standard" old view of the heliosphere: the magnetic field lines in the heliosheath connect back to the sun everywhere (some field lines are shown in red and blue). In this view, scientists expected the heliopause, the boundary that separates where the solar wind dominates from where the interstellar wind dominates, to be smooth and the associated smooth magnetic field to shield us from the interstellar medium and galactic cosmic rays.
Credit: NASA/Goddard Space Flight Center/ CI Lab
The case of cosmic rays is illustrative. Galactic cosmic rays are subatomic particles accelerated to near-light speed by distant black holes and supernova explosions. When these microscopic cannonballs try to enter the solar system, they have to fight through the sun's magnetic field to reach the inner planets.
"The magnetic bubbles appear to be our first line of defense against cosmic rays," points out Opher. "We haven't figured out yet if this is a good thing or not."
On one hand, the bubbles would seem to be a very porous shield, allowing many cosmic rays through the gaps. On the other hand, cosmic rays could get trapped inside the bubbles, which would make the froth a very good shield indeed.
So far, much of the evidence for the bubbles comes from the Voyager energetic particle and flow measurements. Proof can also be obtained from the Voyager magnetic field observations and some of this data is also very suggestive. However, because the magnetic field is so weak, the data takes much longer to analyze with the appropriate care. Thus, unraveling the magnetic signatures of bubbles in the Voyager data is ongoing.
"We'll probably discover which is correct as the Voyagers proceed deeper into the froth and learn more about its organization," says Opher. "This is just the beginning, and I predict more surprises ahead."
{...}
NASA Goddard Multimedia:
Voyager Satellites Find Magnetic Bubbles at Edge of Solar System (RELATED VIDEOS AND IMAGES)
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It's amazing that two little probes that began their journey decades ago, designed to visit four big balls of gas, are still "alive", still send data back and revolutionize the way we see the universe. :hail: Voyagers!
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NASA / NASA JPL:
Recalculating the Distance to Interstellar Space
June 15, 2011
Scientists analyzing recent data from NASA's Voyager and Cassini spacecraft have calculated that Voyager 1 could cross over into the frontier of interstellar space at any time and much earlier than previously thought. The findings are detailed in this week's issue of the journal Nature.
Data from Voyager's low-energy charged particle instrument, first reported in December 2010, have indicated that the outward speed of the charged particles streaming from the sun has slowed to zero. The stagnation of this solar wind has continued through at least February 2011, marking a thick, previously unpredicted "transition zone" at the edge of our solar system.
"There is one time we are going to cross that frontier, and this is the first sign it is upon us," said Tom Krimigis, prinicipal investigator for Voyager's low-energy charged particle instrument and Cassini's magnetospheric imaging instrument, based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
Krimigis and colleagues combined the new Voyager data with previously unpublished measurements from the ion and neutral camera on Cassini's magnetospheric imaging instrument. The Cassini instrument collects data on neutral atoms streaming into our solar system from the outside.
The analysis indicates that the boundary between interstellar space and the bubble of charged particles the sun blows around itself is likely between 10 and 14 billion miles (16 to 23 kilometers) from the sun, with a best estimate of approximately 11 billion miles (18 billion kilometers). Since Voyager 1 is already nearly 11 billion miles (18 billion kilometers) out, it could cross into interstellar space at any time.
"These calculations show we're getting close, but how close? That's what we don't know, but Voyager 1 speeds outward a billion miles every three years, so we may not have long to wait," said Ed Stone, Voyager project scientist, based at the California Institute of Technology in Pasadena.
Scientists intend to keep analyzing the Voyager 1 data, looking for confirmation. They will also be studying the Voyager 2 data, but Voyager 2 is not as close to the edge of the solar system as Voyager 1. Voyager 2 is about 9 billion miles (14 billion kilometers) away from the sun.
{...}
Recalculating the Distance to Interstellar Space
June 15, 2011
Scientists analyzing recent data from NASA's Voyager and Cassini spacecraft have calculated that Voyager 1 could cross over into the frontier of interstellar space at any time and much earlier than previously thought. The findings are detailed in this week's issue of the journal Nature.
Data from Voyager's low-energy charged particle instrument, first reported in December 2010, have indicated that the outward speed of the charged particles streaming from the sun has slowed to zero. The stagnation of this solar wind has continued through at least February 2011, marking a thick, previously unpredicted "transition zone" at the edge of our solar system.
"There is one time we are going to cross that frontier, and this is the first sign it is upon us," said Tom Krimigis, prinicipal investigator for Voyager's low-energy charged particle instrument and Cassini's magnetospheric imaging instrument, based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
Krimigis and colleagues combined the new Voyager data with previously unpublished measurements from the ion and neutral camera on Cassini's magnetospheric imaging instrument. The Cassini instrument collects data on neutral atoms streaming into our solar system from the outside.
The analysis indicates that the boundary between interstellar space and the bubble of charged particles the sun blows around itself is likely between 10 and 14 billion miles (16 to 23 kilometers) from the sun, with a best estimate of approximately 11 billion miles (18 billion kilometers). Since Voyager 1 is already nearly 11 billion miles (18 billion kilometers) out, it could cross into interstellar space at any time.
"These calculations show we're getting close, but how close? That's what we don't know, but Voyager 1 speeds outward a billion miles every three years, so we may not have long to wait," said Ed Stone, Voyager project scientist, based at the California Institute of Technology in Pasadena.
Scientists intend to keep analyzing the Voyager 1 data, looking for confirmation. They will also be studying the Voyager 2 data, but Voyager 2 is not as close to the edge of the solar system as Voyager 1. Voyager 2 is about 9 billion miles (14 billion kilometers) away from the sun.
{...}
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